(svn r9583) [0.5] -Backport from trunk (r9529, r9533, r9540, r9541):
- Fix: when 2 clients joined together, the second asserted on the NewCompany command of the first (r9529)
- Fix: when company is removed, sell all shares he has first, then sell all shares other people might have in this company (r9533)
- Fix: bankrupt AIs no longer buy over themselves (also added safeguards to prevent in future) (r9540 / r9541)